Refrigerating device



H n M s c L REFRIGERATING DEVI CE Fil ed Sept 24, 1952 2 Sheets-Sheet 1 Zhmentor Lawranc 6. 6/21/76 torneg arch 12, 1935. I Q SMITH 1,994,44U

REFRIGERATING DEVICE Filed Sept. 24, 1932 2 Sheets-Sheet 2' Zhwentor luau-me; C. 5021775 Patented '12, 1935 PATENT ol-rlca 1,994,440 J REFRIGERATING DEVICE Lawrence C. Smith,

Kenmore, N. Y., assignor to Fedders Manufacturing Company, 1110., Buffalo, N. Y.

Application September 24, 1932, Serial No. 634,715 Claims. (Cl. 62-126) This invention relates to mechanical refrigeration andit has particular reference to the provision of an improved evaporator for a flooded refrigeration system of the compressor-condenser- 5 evaporator type. v

In such systems, gaseous refrigerant iscompressed to a liquid state, is cooled, and is'deliver-ed into an evaporator in which it returns to the gaseous condition with absorption of heat, and such gas is returned to the compressor for compression and cycle of operation, more or less lubricant, usually a mineral oil, is carried by the liquid refrigerant into the evaporator, and, as the lubricant does not gasify with the refrigerant, it tends to collect in the evaporator, creating the detrimental condition known as oil logging. To overcome such defect in a flooded system, or one wherein the refrigerating effect is produced by evaporation of the refrigerant liquid in the evaporator or header, it has been proposed to provide separate means for returning the oil, which normally floats on the surface of the refrigerant liquid. Oil return devices, as heretofore used, have taken m the form of tubes disposed at about the anticipated oil level, capillary wicks, or an open cup into which the oil may spill or into which it may be splashed, so as to bring such oil within the reach of a suction tube leading to the compressor. Such oil return devices and evaporators have also been associated with suction lines opening into the gas space above the refrigerant body, by means of which the gasified refrigerant, and any oil entrained therewith, may bereturned to the compressor.

The effective return of gasified refrigerant and oil fairly contemplates a'relatively quiescent condition in the evaporator, to avoidthe return of appreciable portions of liquid refrigerant, which, if injected into the suction or return line, tends to evaporate with absorption of heat, leadingto losses in operating efficiency and the trouble known as back-frosting. In practice, however, the oil return means heretofore found applicable are subject to various limitations which militate against their use in all types of flooded systems or compressors, since the operating conditions vary widely, and situations frequently occur where the liquid refrigerant, instead of being m quiescent, is, violently agitated as the refrigerating action takes place.

The present invention deals with the provision of means to minimize or circumventthe adverse eflects of such agitation or excessive turbulence,

55 and, in general, it contemplates the division of circulation anew. During the traces of the cylinder 10),

the evaporator header into two intercommunicating portions, one of which is directly in communication with the refrigerant tubes, and the other of which is adapted to receive the. oil and refrigerant return devices. This division is ef- 5 *fected by means of a wall around or through which refrigerant may freely flow, but, during such motion, the turbulence created by the ejection of refrigerant from the tubes is curtailed, so that the liquid and gas within the inner chamber 10 or portion is maintainedsufiiciently quiescent at all times to avoid the introduction of liquid refrigerant to the return lines, thereby eliminating back-frosting and enhancing the general efiiciency' of operation.

The principles of the invention will be more fully understood from the following description of practical embodiments thereof, representing forms now known to me as best securing the intended results, and illustrated in the accompanying drawings, wherein: Y

Fig. 1 is a transverse cross section of a flooded 1 evaporator with the invention embodied therein;

Fig. 2 is a longitudinal section of the device shown in Fig. 1; and,

Fig. 3 is a plan view, partially in section, showing a modified form of the invention.

The evaporator herein illustrated is in the form of an elongated tube or cylinder 10, closed at its open end by a head or plate 11 which carries refrigerant inlet and outlet devices, and connected to a plurality of depending U tubes 12,-in which the evaporating action primarily takes place." Liquid, cinsisting of a mixture of refrigerant and oil, is delivered to the evaporator from the compressor (not shown) through an inlet pipe 13 which communicates with a boss 14 disposed within the header, and in which is positioned a valve 15. The level of the liquid within the evaporator is controlled by a float 16, shown to asbeing in the form of an open and buoyant cup, which is pivoted to the plate 11 by means of a connection 17, and which is connected to. the valve 15 by a clip- 18, so that, after a certain level of refrigerant is obtained, the valve 15 is closed to t5 shutoff the liquid supply. Conversely, when the refrigerant level is lowered, (from a zone say about halfway between the upper and lower the valve 15 is opened, and additional liquid is admitted. I

A suction tube 19, leading from the evaporator to the compressor, is also secured within the cylinder 10 and to the plate 11, and it is provided with a depending portion 20 which reaches within the cavity of the float 16. It will be apparent that whatever liquid or gas finds its way above the normal liquid level, and into the cavity of the float, will be returned by suction to the compressor, which is the action intended.

As noted above, the major operation of boiling of the refrigerant occurs in the depending tubes 12, which are relatively deep compared to their diameter, and it has been found that, in many instances, there is formed in such tubes a volume of gas, and 'a pool of oil released from the refrigerant. Such condition is unstable, and the gas, instead of disintegrating into small bubbles which percolate up the tube and through the liquid in the cylinder 10, is frequently suddenly discharged into the header with what may be termed a volcanic effect, violently agitating the liquid in the cylinder and discharging therethrough a slug of oil and a shower of liquid refrigerant. This liquid, and particularly the refrigerant, is caught within the cavity of the float 16 and is taken up by the suction line to return active refrigerant to the compressor, with the undesired results of losses in operating efficiency and back-frosting.

As thus far described, the evaporator represents astructure old with me, and it has been set forth to illustrate the problems presented, and which my invention is designed to solve. It may here be explained that, to prevent the return of liquid refrigerant, it is necessary to prevent the discharge of such liquid into the float 16, where it'may be introduced into the suction line 19, and hence it is necessary to guard the float from the volcanic efiects just described, as whatever is caught by the float must necessarily be returned to the compressor. It is desired that the float receive only gasifled refrigerant, which contains a high percentage of entrained oil, and hence, to effect the oil return, I have endeavored to provide means within the cylinder 10 which will act as a separator for the liquidrefrigerant, and which will maintain the liquid around the float 16 in a substantially quiescent condition, in which no more than a uniform ebullition will occur.

Referring particularly to Figs. 1 and 2, wherein the end of the float 16 is in close proximity to the end of the tubular shell 10, the protective device consists of asection of sheet metal bent in the form of a flattened tube 31, one end of which is flared about its circular portion to form a flange 32. The shell is formed with an annular internal rib orshoulder 22 having an inside diameter about equal to the outside diameter of the tube 31 so that when the tube is inserted in the shell 10, the flange 32 thereof engages the shoulder 22 ,and thus acts to position the tube axially. When the head 11 is applied to this assembly. it abuts the shoulder 22 and clamps the tube to the shoulder22, as shown in Fig. 2. The body of the tube 31 is spaced from the wall of the shell 10 by means of a plurality of aligned rows of protruding beads 34 which engage such wall.

The free end 35 of the tubeterminates short of the end of the shell 10 andcompletely encloses the float 16. Upon inserting the tube 31 into the shell 10, the unconnected ends 37 thereof are overlapped to a sufficient degree to permit the beads 34 to clear the shoulder 22, whereupon the tube is restored to its natural shape with the ends 37 forming a lap joint as illustrated in Fig. 1.

As more clearly shown in-Fig. 1, the tube 31 forms within the evaporator, in cooperation with the shell 10 thereof, a restricted annular chamber 38 which leads to the top of the evaporator where the tube is flattened, as indicated by the numeral 39, to form, in effect, a gas header or manifold 41. The end of the chamber 38 and the header-41 both communicate with the open space 42 at the end of the shell 10 and thus communicate with the float chamber 43 formed within the tube 31.

In operation, and/or refrigerant and oil volumes forced out of the tubes 12 by theboiling or ebullition action therein impinge themselves on the wall-of the tube 31, where in the case of a miniature explosion, as heretofore explained, the force of the thrust is expended upon striking the wall and the refrigerant and oil is spread over a large metallic surface within the confines of the outer chamber 38. The liquid in the chamber 38 during this action is attimes sufliciently agitated to enter the gas header 41; however, this agitation is neutralized during the passage of the refrigerant and gas through the restricted chamit will be found that the gas ber 38 so that upon entry into the float chamber 43 the turbulence is substantially decreased and the liquid level within the float chamber is not sufiiciently affected to cause a movement of the float 16.

Where there is suflicient space between the end of the float 16 and the end of the shell 10, the above described structure of the device 31 may be modified. For example, as shown in Fig. 3, the protective device consists of a simple, flattened tube 45, one end 46 of which abuts the end 4'! of the shell 10 and which is retained in concentricity therewith by the socket effect of the rounded end thereof, The opposite extremity of the tube 45 is firmly engaged by the head 11 during the sealing operation of the header-and this end is retained in concentricity by the shoulder 22 which it snugly engages. with a plurality of ports 48 through which the refrigerant and gas enter the float chamber 51,-

in a manner similar to that described in connection with the first embodiment of the invention.

It will be apparent that the invention provides for a simple structure, readily associated with existing devices, by means of which the effect of excessive turbulence of the liquid refrigerant, inducing back-frosting, may be eliminated. It will also be apparent that such structure does not interfere with the normal actions occurring during the refrigerating process, but, on the contrary, tends to enhance such actions and to eliminate 'the undesired effects of violent discharge of refrigerant into the suction tube. It will further be understood that the principles of the invention may be applied in various forms, and it is therefore desired that the illustrated embodiments therebf should not betaken as limitations The end 46 isformed exceptas they may be included within the scope of the following claims.

I claim:

1. In a refrigeration system, an evaporator.

comprising an elongated header, a partition positioned within the header in spaced relation to the walls thereof and forming therewith an innerchamber and a narrow communicating outer chamber, a plurality of tubes mounted on the header and communicating with said outer cham ber, a refrigerant inlet control valve, aniopen float in the inner chamber for controlling the operation of said valv and a suction line having an extension within said inner chamber entering said float.

2. In a refrigeration system, an evaporator comprising an elongated header, a partition puitioned within said header and forming an inner chamber and avnarrow communicating chamber between the walls of the header and said partition, a plurality of tubes secured to the header and communicating with said outer chamber, an oil return device in the inner chamber, a refrigerant suction line entering the inner chamber and communicating with said return device, and means for introducing refrigerant into the evaporator in response to liquid level conditions said inner chamber.

3. An evaporator comprising a header, 9, plurality of tubes depending from said header and having their open ends in communication with the interior-of the header, a float chamber within the header, a manifold in the header for receiving the output of the tubes, said manifold extending in angular relation to said tubes and having an end portion communicating with said float chamber, and refrigerant input and suction conduits communicating with said header.

4. An evaporator comprising a header having an open end, an annular rib in said header adiacent said open end, ahead having a portion enterlng said open'end in proximity to said rib, an open cylinder inserted in said header in spaced relation to the walls thereof and formed with a flange at one extremity for abutting the rib on the header, said head upon being secured to said header clamping said flange to said rib, and tubes communicating with the header through the side wall thereof.

5. An evaporator comprising a header having an open-end, an annular rib in said headeradiacent said open end, ahead having a portion entering said open end and abutting said rib, an open cylinder inserted in said header and having opposite ends engaged between said head and the walloi the closed end of the header, said rib engaging. the wall 01' the cylinder and spacing it from the wall of the header, said cylinder being formed with openings for establishing communication between the isolated chambers thus er through the side wall thereof. I

LAWRENCE C. .8561.-

' formed, and tubes communicating with the head- 20 

